See this http://jsbin.com/ocuxad/4/edit.

Or,

in javascript

x=$('select#per_page').prev('#page');
console.log($('select#per_page'));
console.log(x); // returns []

in html

<input id="page" name="page" type="hidden" value="1">
 <input id="per_page" name="per_page" type="hidden" value="25">
 <select id="per_page" name="per_page">
  <option value="10">10</option>
  <option value="25">25</option>
  <option value="50">50</option>
 </select>